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Abstract:

A cutting apparatus for joint cutting system using robot includes a shaft
combined with a motor in a part of a robot arm, a cutter having a cutting
head at the end of the shaft, a sleeve in which the shaft is inserted,
and a cutter support member having a sleeve base where the sleeve is
fixed, characterized in that the sleeve is a standalone member of a
hollow bar with a center hole and is separable from and combinable with
the sleeve base. The sleeve and the sleeve base are so separable that it
is possible to reinforce the strength of the sleeve, which retrains the
bending force to the sleeve, though the diameter of the sleeve is
minimized.

Claims:

1. A cutting apparatus for joint cutting system using robot comprising; a
shaft combined with a motor in a part of a robot arm, a cutter having a
cutting head at the end of the shaft, a sleeve in which the shaft is
inserted, and a cutter support member having a sleeve base where the
sleeve is fixed, characterized in that the sleeve is a standalone member
of a hollow bar with a center hole and is separable from and combinable
with the sleeve base.

2. A cutting apparatus of claim 1, wherein the sleeve has support
bearings which are equipped in the center hole and support the shaft 11
such that the shaft 11 is rotatable, and in order to reinforce the
strength against the bending force the support bearings are located in
the front side and the back side of the sleeve, which minimizes the
reduction of the thickness of the sleeve.

3. A cutting apparatus of claim 2, wherein the sleeve base comprises a
base body with middle hole part, first base join part formed on the inner
circular surface around the front end of the sleeve base and combined
with the back end of the sleeve, second base join part formed on the
inner circular surface around the back end of the sleeve base and
combined with the part of the robot arm, and a washing water discharging
hole formed in the base body for discharging washing water; and the
sleeve comprises a sleeve body of a hollow bar shape, a join body with
sleeve join part combined with the first base join part at the back end
of the sleeve body, bearing install grooves located apart each other on
the inner circular surface of the sleeve body for equipping the support
bearings, reinforcing part for reinforcing against the bending force to
the sleeve body which is protruded toward center of the center hole from
the inner circular surface between the bearing install grooves.

4. A cutting apparatus of claim 3, wherein the bearing install grooves
consist of first bearing install groove formed on the inner circular
surface of the join body with the sleeve join part and second bearing
install groove formed on the inner circular surface around the front side
of the sleeve body, and the support bearings consist of first support
bearing combined at the front side of the first bearing install groove,
second support bearing combined at the back side of the second bearing
install groove, third support bearing combined at the back side of the
first bearing install groove, and the fourth support bearing combined at
the second bearing install groove.

5. A cutting apparatus of claim 4, Wherein each of the first to fourth
support bearings has multiple bearings consecutively arranged, the
outside surface of which comes into contact with the first or second
bearing install groove and the inside surface of which comes into contact
with the outer circular surface of the shaft, further comprising
reinforcing spacers which are equipped on the inner circular surface of
the sleeve between the second and fourth support bearings and between the
first and third support bearings and which has a center hole where the
shaft is inserted.

6. A cutting apparatus of claim 1, further comprising: end spacers for
retraining the fluctuation of the shaft which are inserted in the front
and back ends of the center hole of the sleeve and have a center hole
where the shaft is inserted.

7. A cutting apparatus of claim 1, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

8. A cutting apparatus of claim 7, wherein the number of the cutters is 5
and the outer diameter of the cutting head is 6.2 mm within a tolerance
of 10%.

9. A cutting apparatus of claim 7, wherein the cutters have roughing
groove for improving machinability, and the outer diameter of the cutting
head is 6.2 mm within a tolerance of 10%.

10. A cutting apparatus of claim 2, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

11. A cutting apparatus of claim 3, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

12. A cutting apparatus of claim 4, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

13. A cutting apparatus of claim 5, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

14. A cutting apparatus of claim 6, wherein the cutting head has multiple
cutters protruded equi-angularly at a head core, and the outer diameter
of the cutting head corresponds to the diameter of a fixing protrusion of
the knee joint implant or is bigger than the diameter of the fixing
protrusion by within 10%.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from Korean Patent Application No.
10-2012-0137674, filed on Nov. 30, 2012 in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference.

BACKGROUND

[0002] 1. Field

[0003] The present invention relates to a cutting apparatus for joint
cutting system with robot. In detail, a sleeve and a sleeve base are so
separable that it is possible to reinforce the strength of the sleeve,
which retrains the bending force to the sleeve, though the diameter of
the sleeve is minimized. Therefore, the durability of the sleeve is
increased and the tough and damage to the bone, the muscle and the skin
tissue around the surgical site are decreased owing to the decrease of
the diameter of the sleeve. Also when the sleeve is bended the sleeve
alone is so changeable that the maintenance cost is reduced and the
maintainability is improved. In addition, the machinability of the bone
is improved and it is so needless to change the cutter during the surgery
that the surgery can be performed rapidly, exactly, and safely.

[0004] 2. Description of the Related Art

[0005] The number of patient with joint disease comprising arthritis,
osteoporotic fracture and etc. has been sharply increased as an aged
population has been increased owing to the long average life span of
human being.

[0006] The joint disease in early stage would be cured with non-surgery
treatment comprising medication, physical therapy and so on, but the
severe joint disease should be performed a surgery on.

[0008] The artificial joint surgery is performed in a way that the cutter
of the cutting apparatus equipped in the end of variable-positioned arm
of a robot rotates with cutting the knee joint according to the
information from a computer, and then an artificial knee joint is put in
(refer to FIG. 2).

[0009]FIG. 1 represents an existing cutting apparatus of joint cutting
system with robot, and FIG. 2 represents roughly an artificial joint
which is performed with on the knee joint. As depicted, a head 110 is 7.8
mm in a diameter and has a cutter on outer surface and front end surface
formed at one end of the position-variable arm of the robot. A shaft 120
which is a hollow bar of 2.3 mm in a diameter is extended from head 110
and the back end of the shaft 120 is connected with a motor (M) equipped
at the other end of the position-variable arm of the robot.

[0010] And outer circumferential surface of the shaft 120 is supported by
a sleeve 130 fixed by the housing of the motor (M) such that the shaft
120 is rotatable. So the rotation of shaft 120 doesn't make any trembling
and bending. The cutting is performed by the rotation of the head 110
which is protruded out from the sleeve 130.

[0011] The cutting apparatus of FIG. 1 has some drawbacks that the
diameter of the head 110 is so large, as mentioned above, around 7.8 mm
that it might touch skin tissue during an operation. And therefore the
skin and the fresh are to be inevitably cut. Also a surgery to control
the cutting path such like a tunnel cutting is not available. Also
intense rolling friction between shaft 120 and sleeve 130 would abrade
the surfaces after long-term using and make the unordinary rotations.

[0012]FIG. 3 shows other example of existing cutting apparatus of joint
cutting system with robot which is disclosed in Korean registered patent
No. 10-0873014.

[0013] Referring to FIG. 3, the joint cutting apparatus has a
position-variable arm, a motor (M) at the front end of the arm, a sleeve
14 combined at housing of the motor, and a cutter 10 connected with a
shaft of the motor to be rotatable in the sleeve. The cutter 10 comprises
a shaft 11 of a hollow bar of cantilever type which is connected with the
motor to be rotatable in the sleeve 14 and extended outward the sleeve,
and a head 12 formed at the front end of the shaft 11. The cantilever
length of the shaft 11 and the diameter of the head 12 are chosen as one
of each 20-30 mm and 1.5-4.0 mm, or each 70-80 mm and 4.0-6.0 mm in order
that the head 12 bores a hole into the bone.

[0014] As stated above, the cutting apparatus in FIG. 3 works with
tunneling-like cutting method using cutter with minimal diameter and
optimized cantilever length so that the bone would be cut safely and
fast, and damage to the bone would be lessen, advantageously. But the
shaft 11 is not supported by the sleeve 14 and has cantilever structure
which cause disadvantageously trembling and bending. Especially, as the
shaft 11 would be rotated over 60,000 rpm during an operation, there
would be some drawbacks such like the breakdown of the shaft 11, unsafety
and so on. Also, the trembling of the shaft 11 limits to the length of
the protrusion in the cantilever structure so that it would be not
available in deep surgical site.

[0015] Recently, in order to supplement the drawbacks of the cutting
apparatus in FIG. 1 and FIG. 3, the diameter of the sleeve is decreased
so that tough and damage to the bone, muscle, and skin tissue are
lessened, and a cutter support member having multiple bearings in the
sleeve has been developed.

[0016] However, the cutter support member of this type where the sleeve in
the form a hollow bar and the sleeve base in the form of a cap are an
integral unit has some defects such like difficult manufacturing, high
manufacturing cost, long manufacturing. Especially, the integration of
the sleeve and the sleeve base make it difficult to insert a tool into
the inner hole of the sleeve or to form the settling groove of bearings
on the inner surface of the sleeve so that the bearings should be
inserted without the settling groove. Therefore, the diameter of the
sleeve could not be decreased and the large diameter would make touch and
damage to the bone, muscle, skin tissue around surgical site.

[0017] Besides, when the bearings inside the sleeve get damaged owing to
the high speed rotation of the shaft of the cutter over 60,000 rpm or the
sleeve gets bended by the bending force owing to the movement of the
cutting head during the surgery, the sleeve base with the broken-down
sleeve should be replaced with new integral unit so that the maintenance
cost would be very high, disadvantageously.

[0018] Meanwhile, in the said existing cutting apparatuses one of the
cutting heads of 7.8 mm and 2.3 mm in diameter is optionally used
depending on the process and the cutting head should be changed properly
during the surgery which is inconvenient to the operator and increases
the surgery time. In other words, the cutting head of 7.8 mm in diameter
is used in cutting the surface of the knee joint bone (ex, femur, tibia)
on which the artificial joint is settled, and the cutting head of 2.3 mm
in diameter is used in drilling the inserting hole (peg, hole in the knee
joint bone), in which a fixing protrusion (a2) of the artificial joint
(a) is inserted, after inconveniently changing the cutting head of 7.8 mm
in diameter.

SUMMARY

[0019] An object of the present invention is to provide a cutting
apparatus of a joint cutting system using robot, the diameter of the
sleeve of which is decreased so as to reduce the touch and damage to the
skin tissue.

[0020] Another object of the present invention is to provide a cutting
apparatus of a joint cutting system using robot, the low maintenance cost
and the improved maintainability of which are achieved by changing not
the sleeve base but the bended sleeve alone.

[0021] Another object of the present invention is to provide a cutting
apparatus of a joint cutting system using robot, with which the safe and
rapid surgery is achieved by artificial joint surgery without changing
the cutter and improved machinability.

[0022] The above objects are achieved by a cutting apparatus for joint
cutting system using robot according to an aspect of the present
invention, comprising; a shaft combined with a motor in a part of a robot
arm, a cutter having a cutting head at the end of the shaft, a sleeve in
which the shaft is inserted, and a cutter support member having a sleeve
base where the sleeve is fixed, characterized in that the sleeve is a
standalone member of a hollow bar with a center hole and is separable
from and combinable with the sleeve base.

[0023] The sleeve might have support bearings which are equipped in the
center hole and support the shaft 11 such that the shaft 11 is rotatable,
and in order to reinforce the strength against the bending force the
support bearings are located in the front side and the back side of the
sleeve, which minimizes the reduction of the thickness of the sleeve. And
the sleeve base might comprise a base body with middle hole part, first
base join part formed on the inner circular surface around the front end
of the sleeve base and combined with the back end of the sleeve, second
base join part formed on the inner circular surface around the back end
of the sleeve base and combined with the part of the robot arm, and a
washing water discharging hole formed in the base body for discharging
washing water, and the sleeve might comprises a sleeve body of a hollow
bar shape, a join body with sleeve join part combined with the first base
join part at the back end of the sleeve body, bearing install grooves
located apart each other on the inner circular surface of the sleeve body
for equipping the support bearings, reinforcing part for reinforcing
against the bending force to the sleeve body which is protruded toward
center of the center hole from the inner circular surface between the
bearing install grooves.

[0024] Also the bearing install grooves might consist of first bearing
install groove formed on the inner circular surface of the join body with
the sleeve join part and second bearing install groove formed on the
inner circular surface around the front side of the sleeve body, and the
support bearings might consist of first support bearing combined at the
front side of the first bearing install groove, second support bearing
combined at the back side of the second bearing install groove, third
support bearing combined at the back side of the first bearing install
groove, and the fourth support bearing combined at the second bearing
install groove.

[0025] Furthermore, each of the first to fourth support bearings might
have multiple bearings consecutively arranged, the outside surface of
which comes into contact with the first or second bearing install groove
and the inside surface of which comes into contact with the outer
circular surface of the shaft. And the above cutting apparatus might
further comprise reinforcing spacers which are equipped on the inner
circular surface of the sleeve between the second and fourth support
bearings and between the first and third support bearings and which has a
center hole where the shaft is inserted.

[0026] Meanwhile, the cutting apparatus might further comprise end spacers
for retraining the fluctuation of the shaft which are inserted in the
front and back ends of the center hole of the sleeve and have a center
hole where the shaft is inserted.

[0027] Preferably, the cutting head has multiple cutters protruded
equi-angularly at a head core, and the outer diameter of the cutting head
corresponds to the diameter of a fixing protrusion of the knee joint
implant or is bigger than the diameter of the fixing protrusion by within
10%.

[0028] Preferably, the number of the cutters is 5 and the outer diameter
of the cutting head is 6.2 mm within a tolerance of 10% or the cutters
have roughing groove for improving machinability.

[0029] The cutting apparatus for the joint cutting system according to the
present invention has the following advantages:

[0030] The sleeve and the sleeve base are so separable that it is possible
to reinforce the strength of the sleeve, which retrains the bending force
to the sleeve, though the diameter of the sleeve is minimized. Therefore,
the durability of the sleeve is increased and the tough and damage to the
bone, the muscle and the skin tissue around the surgical site are
decreased owing to the decrease of the diameter of the sleeve so that the
safeness of the surgery is improved and patient's recovery time is
shortened. And, after overlong use not a unit of the sleeve and the
sleeve base, such like existing all in one type, but the sleeve alone is
so changeable that the advantage is achieved that the maintainability is
improved and the maintenance cost is decreased.

[0031] Also, trembling of the cutter is minimized, the machinability of
the cutting head is improved, the surgery time is shortened, it is
needless to change the cutter because with just one cutter it is possible
to cut not only femur, tibia but also inserting hole (peg) where the
fixing protrusion of the implant is inserted and therefore the surgery
can be performed rapidly, exactly, and safely.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a schematic view of a cutting apparatus of an existing
joint cutting system using robot.

[0033]FIG. 2 is a perspective view of an exemplary artificial joint
placed surgically on knee joint.

[0034]FIG. 3 is a schematic view of a cutting apparatus of another
existing joint cutting system using robot.

[0035]FIG. 4 is a front view of a cutting apparatus of a joint cutting
system using robot according to an embodiment of the present invention.

[0036]FIG. 5a is a perspective view of a cutting apparatus of a joint
cutting system using robot according to an embodiment of the present
invention.

[0037]FIG. 5b is a sectional view of a cutting apparatus of a joint
cutting system using robot according to an embodiment of the present
invention.

[0038]FIG. 6 is a sectional view of a sleeve adapted to a cutting
apparatus of a joint cutting system using robot according to an
embodiment of the present invention.

[0039] FIGS. 7a to 7c are views of a sleeve base adapted to a cutting
apparatus of a joint cutting system using robot according to an
embodiment of the present invention.

[0040] FIG. 8a is a perspective view of an exemplary cutter adapted to a
cutting apparatus of a joint cutting system using robot according to an
embodiment of the present invention.

[0041] FIG. 8b is a perspective view of another exemplary cutter adapted
to a cutting apparatus of a joint cutting system using robot according to
an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0042] Hereinafter, an embodiment of the present invention would be
explained referring to appended drawings.

[0043]FIG. 4 is a front view of a cutting apparatus of a joint cutting
system using robot according to an embodiment of the present invention,
FIG. 5a is a perspective view of a cutting apparatus of a joint cutting
system using robot according to an embodiment of the present invention,
and FIG. 5b is a sectional view of a cutting apparatus of a joint cutting
system using robot according to an embodiment of the present invention.

[0044] Referring to FIG. 4 to FIG. 5b, a cutting apparatus of a joint
cutting system according to an embodiment of the present invention is an
apparatus installed at the arm (not shown) of a surgical robot which cuts
bone to implant artificial joint such like a knee joint, and comprises a
cutter 1 and a cutter support member 2, wherein the cutter 1 has shaft 11
connected with a motor (not shown) of the robot arm and a cutting head 12
formed at the end of the shaft 11, and the cutter support member 2 has a
sleeve 21 where the shaft 11 is inserted and a sleeve base 22 which the
sleeve 21 is fixed on.

[0045] Especially, in the cutting apparatus of the joint cutting system
using robot according to the present invention, the sleeve 2 and the
sleeve base 22 of the cutter support member 2 are so separable that the
sleeve 21 is a standalone member of a hollow bar having a center hole 211
inside and is optionally combined with or separated from the sleeve base
22.

[0046] And, support bearings 3 are equipped inside the center hole 211 of
the sleeve 21 for supporting the shaft 11 to be rotatable. The point is
that considering the strength against the bending force, the support
bearings 3 are located at the front side and back side of the sleeve 21
in order to minimize the decrease of thickness of the sleeve 21.

[0047]FIG. 6 is a sectional view of a sleeve adapted to a cutting
apparatus of a joint cutting system using robot according to an
embodiment of the present invention.

[0048] Referring to FIG. 6, the sleeve 21 is a member of a hollow bar type
with a center hole 211 and comprises a sleeve body 212, a join body 213,
bearing install groove 214, and reinforcing part 215.

[0049] The sleeve body 212 is a part inserted into the human body in
surgery and is made a hollow bar member with uniform outer diameter. The
length of the sleeve body 212 depends on the surgical site, the way of
surgical operation and etc., and the length of the sleeve body 212 for
knee joint surgery is preferably around 77 mm with 10% tolerance for
error. Any material which is not harmful to the human body is adaptable
for the sleeve body 212 and in this embodiment stainless of standard
SUS303 is used.

[0050] The join body 213 is a part extended from the back end of the
sleeve body 212 and forms one body with the sleeve body 212. It has
sleeve join part 213a which is combined with latter mentioned first base
join part 223 of the sleeve base 22, sealing insert groove 213b in which
a sealing 23 is inserted, and o-ring insert groove 213c in which an
O-ring 24 is inserted.

[0051] The bearing install groove 214 is formed on the inner circular
surface of the sleeve 21 for installing the support bearing 3 and a
couple of the bearing install grooves is located around front side and
back side of the sleeve 21 apart each other.

[0052] Also, the bearing install groove 214 consists of first bearing
install groove 214a on the inner circular surface of the sleeve 21 near
the join body 213 and second bearing install groove 214b on the inner
circular surface around the front side of the sleeve body 212

[0053] The reinforcing part 215 is formed in a state to protrude inward
center hole 211 between the first bearing install groove 214a and the
second bearing install groove 214b and to make the sleeve body 212
thicker for reinforcing the sleeve body 212 against bending force.

[0054] Meanwhile, the support bearing 3 comprises first support bearing 31
installed around the front end (bordering the reinforcing part 215) of
the first bearing install groove 214a, second support bearing 32
installed around the back end (bordering the reinforcing part 215) of the
second bearing install groove 214b, third support bearing 33 installed
around the back end of the first bearing install groove 214a, and fourth
support bearing 34 installed around the front end of the second bearing
install groove 214b,

[0055] Each of the first to fourth support bearing 31, 32, 33, 34 has
consecutively arranged multiple bearings, which are installed to be
inserted between the shaft 11 and the bearing install groove 214.
Good-durability bearing which is capable of supporting the high speed
rotation of the shaft 11 is not limited for the first to fourth support
bearing 31, 32, 33, 34, and, however, in this embodiment two ball
bearings are consecutively arranged in the first to fourth support bear
31, 32, 33, 34.

[0056] Also, reinforcing spacers 4, 4' are inserted between the support
bearings to prevent bending of the sleeve body 212. The reinforcing
spacer 4 is between the second and fourth support bearing 32, 34 on the
inner circular surface of the sleeve 21 and the reinforcing spacer 4' is
also between the first and third support bearing 31, 33, wherein the
length of the reinforcing spacer 4, 4' corresponds to the separation
distance of the support bearings. The reinforcing spacers 4, 4' have
formed to have a center hole where the shaft 11 is inserted. Therefore,
the reinforcing spacers 4, 4' fix the location of the support bearing 3
so as to prevent the support bearing 3 loose, and restrain the trembling
of the shaft 11 around the section with no bearing.

[0057] Meanwhile, the sleeve 21 comprises end spacers 5, 5' for
restraining the fluctuation of the shaft 11 in rotation. The end spacers
5, 5' are inserted in the ends of the center hole 211 and are much
shorter than the reinforcing spacers 4, 4'. The end spacer 5 is in the
center hole 211 at the front end of the sleeve body 212 and the end
spacer 5' is in the center hole 211 at the back end of the sleeve body
212, wherein the end spacers 5, 5' are put in and fixed with forced
insertion, welding or adhesive for metal (loctite 609).

[0058] The end spacer 5 withstands the force from the rotation and
movement of the shaft 11 to the front end of the sleeve 21 and, as a
result, the bending and trembling of the shaft 11 can be restrained.

[0059] FIGS. 7a to 7c are each sectional view, left side view, and the
right side view of a sleeve base adapted to a cutting apparatus of a
joint cutting system using robot according to an embodiment of the
present invention.

[0060] Referring to FIGS. 7a to 7c, the sleeve base 22 has a base body 222
in which first base join part 223, second base join part 224, and washing
water discharging hole 225 are formed.

[0061] The base body 222 has a shape of a conic cap with middle hole part
221 in the center, and the middle hole part 221 comprises a hole part
with large inner diameter to insert the join part of the robot arm into
and another hole part with relatively small inner diameter to insert the
join body 212 of the sleeve 21 into.

[0062] The first base join part 223 is the form of a female thread on the
inner circular surface of the front side of the base body 222, which is
combined with the sleeve join part 213a at the back side of the sleeve
21.

[0063] The second base join part 224 is the form of a female thread on the
inner circular surface of the back side of the base body 222, which is
combined with the join part (not shown) of the robot arm.

[0064] The washing water discharging hole 225 is formed of a hole like a
tunnel passing forward from the middle hole part 221 through the base
body 222 for discharging washing water during artificial joint surgery.
The washing water discharging hole 225 has multiple holes and in this
embodiment 3 holes are distributed at equiangular positions. And besides
the function of the washing, the washing water discharged through the
washing water discharging hole 225 performs the function of cooling for
preventing the cutting friction heat doing damages to the cut site of the
bone

[0065] FIG. 8a is a perspective view of an exemplary cutter adapted to a
cutting apparatus of a joint cutting system using robot according to an
embodiment of the present invention.

[0066] Referring to FIG. 8a, the cutting head 12 has multiple cutters 122
protruded equi-angularly at a head core 121, and the outer diameter of
the cutting head 12 corresponds to the diameter of the fixing protrusion
(a2 in FIG. 2) of the knee joint implant (a in FIG. 2) or is bigger than
that by in the range of 10%.

[0067] Preferably, the cutting head 12 has 6.2 mm in the outer diameter
within a tolerance of 10% and the cutters formed equi-angularly in the
head core 121 are five. The diameter of the fixing protrusion (a2) of the
implant (a) is generally below 6.0 mm and thickness of the inserted
adhesive is to be duly considered in drilling the inserting hole (not
shown) in the knee bone where the fixing protrusion is inserted.

[0068] As shown in FIG. 8a, if the outer diameter of the cutting head 12
is around 6.2 mm, it is easy to cut the femur, the tibia and so on and,
in addition, cut the inserting hole (peg) where the fixing protrusion of
the artificial joint implant (a) so that it is needless to change the
cutter of 7.8 mm in the diameter and the cutter of 2.3 mm in the diameter
during the surgery and the surgery is performed rapidly with one cutter.

[0069] FIG. 8b is a perspective view of another exemplary cutter adapted
to a cutting apparatus of a joint cutting system using robot according to
an embodiment of the present invention.

[0070] Referring to FIG. 8b, the outer diameter of the cutting head 12'
corresponds, as shown in FIG. 8a, to the diameter of the fixing
protrusion (a2 in FIG. 2) of the knee joint implant (a in FIG. 2) or is
bigger than that by in the range of 10%. The cutters 122 are 4 and it is
characteristic that each cutter 122 has roughing grooves 123. The cutting
head 12' has 6.2 mm in the outer diameter within a tolerance of 10%

[0071] The roughing groove 123 decreases frictional resistance of the
cutter 122 in the rotation of the cutting head 12' and improves the
discharge of debris and washing water so that the machinability is
improved.

[0072] Hereinafter, the function of the cutting apparatus of the joint
cutting system using robot according to an embodiment of the present
invention will be explained.

[0073] First of all, the above mentioned cutter 1 is combined with the
cutter support member 2 and the sleeve base 22 is combined with the join
part of the robot arm with combining the second base join part 224 with
the join part of the robot arm. And then, the shaft 11 of the cuter 1 is
combined to be supplied with power by the motor (not shown) in the join
part of the robot arm.

[0074] After assembling the cutting apparatus, according to the
information from a computer the robot arm and the cutter support member 2
moves and then the cutter 1 rotates with cutting the knee bone.

[0075] The shaft 11 of the cutter 1 can stably rotate in high speed over
60,00 rpm because it is supported by the first to fourth support bearing
31, 32, 33, 34. Also, the front end of the shaft 11 is supported by the
end spacer 5 combined at the front end of the sleeve 212 so that the
trembling of the cutting head 12 is decreased.

[0076] Meanwhile, when cutting the knee bone (femur, tibia), the cutting
head 12 is controlled to move upward and downward or from side to side
and therefore the sleeve 21 receives the bending force repeatedly. The
bending force is concentrated onto the combining part of the sleeve base
22 and the sleeve 21, the cross sectional area of which is changed
rapidly due to the cantilever structure of the sleeve 21, and then great
stress to the combining part is forced. However, the reinforcing part 215
in the sleeve 21 restrains the bending force and therefore the transform
such like bending is prevented.

[0077] Especially, the touch and damage to the bone, the muscle, the skin
tissue around surgical site are minimized without the increase of the
outer diameter of the sleeve 1 because the support bearings 3 are located
at the both ends of the sleeve 21.

[0078] In rotating or moving the cutting head 12 upward and downward or
from side to side, the shaft 11 is supported by the end spacer 5 combined
at the front end of the sleeve body 212, which restrains the bending the
cutting head 12.

[0079] Owing to the diameter of 6.2 mm the cutting head as shown in FIGS.
8a and 8b can cut easily not only the femur and the tibia, but also the
inserting hole (peg) in which the fixing protrusion (a2) of the implant
(a) is inserted so that it is needless to change the cutter of 7.8 mm in
the diameter with the cutter of 2.3 mm in the diameter, the change such
like a existing surgical process, during the surgery and the surgery is
performed rapidly and conveniently.

[0080] And the cutting head 12 with 5 cutters or the cutting head 12' with
roughing groove 123 makes the cutting operation rapid.

[0081] Also, the sleeve 21 and the sleeve base 22 are separable so that
after overlong using the sleeve 21 alone is changeable not a unit of the
sleeve and the sleeve base. Therefore, the advantage is achieved that the
maintainability is improved and the maintenance cost is decreased.

[0082] Although a few exemplary embodiments have been shown and described,
it will be appreciated by those skilled in the art that changes may be
made in these exemplary embodiments without departing from the principles
and spirit of the invention, the scope of which is defined in the
appended claims and their equivalents.